ANSI SQL/XML supports an optional ACCORDING TO XMLSCHEMA clause that allows you to specify the schema to use for validation of the XML type instance. The schema is identified either through a URI reference or through the registered schema ID. If the clause is not specified, the schema to be used for validation is determined from the namespace of the value being validated (the registered schemas are searched for a schema with a matching target namespace and if one is found, it is used for validation).
Teradata Database does not support schema registration; therefore, the ACCORDING TO XMLSCHEMA clause is required and you must specify a schema.